TRP OPERON

Question 1

OPERON

Answer 1

cluster of linked genes that all share a common promoter and operator and are transcribed at the same time

Question 2

where r operons located

Answer 2

downstream of the gene’s promoter region

Question 3

operator

Answer 3

short region of DNA that interacts with repressor proteins to alter transcription of an operon

Question 4

So when an operator region is bound with a repressor protein…

Answer 4

RNA polymerase cannot move downstream from the promoter region, inhibiting transcription of the gene.

Question 5

trp operon contains a series of genes that are involved in the production of the

Answer 5

amino acid tryptophan, which can then be used in protein production.

Question 6

In certain species of bacteria

Answer 6

trp operon regulates the expression of structural genes which code for proteins involved in the production of the amino acid tryptophan.

Question 7

The trp operon is composed of a series of structural genes

Answer 7

(trpE, trpD, trpC, trpB, and trpA) which are controlled by a common promoter and operator.

Question 8

trp operon is controlled by

Answer 8

a regulatory gene located upstream

Question 9

How the trp operon works

Answer 9

high and low levels of tryptophan

Question 10

high level

Answer 10

transcription of the trp structural genes is repressed in order to prevent unnecessary production of tryptophan.

Question 11

low level

Answer 11

transcription of the trp structural genes is activated in order to increase the amount of tryptophan available.

Question 12

How the trp operon works - Repression

Answer 12

trp operon is constantly expressed, producing a repressor protein.

Question 13

when high levels of trp

Answer 13

tryptophan binds to the repressor protein which induces a conformational change in the repressor protein.

Question 14

this allows

Answer 14

repressor protein to bind to the operator region n prevent transcription of the structural genes by blocking the path of RNA polymerase, inhibiting unnecessary production of tryptophan.

Question 15

How the trp operon works - Expression

Answer 15

-When insufficient quantity of tryptophan molecules available to bind consistently to the repressor protein. -
-repressor protein can no longer bind from the operator region.
-allows RNA polymerase to transcribe the trp structural genes so that the level of tryptophan can increase.

Question 16

Attenuation:

Answer 16

occurs in response to the amount of rRNA bound trp fan

Question 17

Attentuation - high levels of Tryptophan levels:

Answer 17

1. TRACRIPTION AND TRASLATION OF TRP OPERON BEGINS
2. Ribosomes arrive at 2 codons in a row, trp fan travels to ribosomes and is added to protien being made
3. mRNA fold in specific way via hydrogen bonds and form terminator hairpin loop
   4 this caues mRNA to sep from template DNA at attenuator sequence
   5, RNA polymerase detaches, causing transcription to stop

Question 18

Attentuation - low levels

Answer 18

1. process of transcription and translation of trp occurs
2. ribosoms arrive at the 2 tryptophan codons in row
3. mRNA molecules fold in secific way and form antiterminator hairpin loop
4. this doesnt cause mRNA to sep from temolate starnd
5. RNA polymeras contonues to read dna, allowing transcription